All but the Martian Notifier claim some degree of water resistance: the LG, Samsung, and Motorola models can survive underwater up to 1 meter for 30 minutes, the Cookoo2 up to 100 meters, and the MetaWatch up to 3ATM, which is equivalent to 30 meters. Only the Martian and Motorola models claim to have scratch-resistant screens (the Martian has an anti-scratch acrylic crystal and the Moto 3 uses Gorilla Glass 3).

But the Ionic, the first of Fitbit's devices to include an SpO2 monitor, came out more than one year ago. It's frustrating to hear about exciting features that are "coming soon," when "soon" ultimately means not weeks or months, but years. While I understand it takes time and effort to develop features like this (especially if Fitbit hopes to pursue medical device clearance or approval from the FDA in the future), I don't think Fitbit should hype features that it isn't ready to let users put to the test.

Our top pick for most people is the Apple Watch Series 4 with GPS (starting at $399), which has a huge display, ultra-fast processor, Raise to Speak Siri, fall detection and a built-in electrical heart rate sensor for taking on-the-go electrocardiograms. It also runs watchOS 5, which makes the watch even more useful with automatic workout-tracking, offline podcast playback and a Walkie-Talkie voice chat feature.